The present invention relates generally to the field of wire winding machines and specifically to an apparatus and method of continuously winding wire onto two mandrels, using a single transfer arm to transfer the wire from one mandrel to the other.
Insulated wire, cable, and similar filamentary material are typically manufactured in very long continuous lengths, and spooled onto large reels. Subsequently, the wire is transferred from these large reels and spooled into coreless packages of predetermined length, which are boxed for retail sale or distribution. The term “package” is a term of art referring to the coil of wire itself, and in particular, the pattern in which the wire is spooled. For example, one common pattern is a “figure 8” wherein successive windings cross over when forming coils on either end. The cross-over points progress radially around the circumference of the coil, with the exception of a void or space formed at one radial point. When the package of wire is placed in a box, the void may accept a pay-out tube affixed to the box and projecting into the interior of the wire coil. The innermost end of the wound cable is then fed through the payout tube, and wire is deployed from the package during use from the interior of the coil.
In forming a package of wire by winding the wire on a mandrel, the formation, size, and placement of the payout tube access void is determined by the relationship between the wire feed along the mandrel in axial direction and the radial position of the mandrel as it winds the wire. This relationship, for a desired package, is influenced by a variety of factors, including the diameter of the wire, the length of wire in the package, the size and shape of the package, and the like. Additionally, the dependencies upon and among these factors are not constant. For example, as the wire is wound, the diameter of the package—and hence its circumference—increases. The resulting increased wire length per wrap must be accounted for to maintain the pay-out access void in one radial position. Various mechanical and geometric systems have been devised in the art to specify the relationship between the axial position of a wire feed and the radial position of a winding mandrel to achieve various packages. A significant advancement in the state of the art of winding wire packages was reached with U.S. Pat. No. 5,499,775, assigned to the assignee of the present application, and incorporated herein in its entirety. This patent discloses that a set of winding parameters, or profiles, may be stored in the memory of a processor or numeric controller, which in turn directly controls the wire feed axial position and the winding mandrel radial position to obtain a desired package for any of a wide variety of wire sizes, lengths, and package types.
The above-referenced patent discloses only a single wire winding mandrel. Operation of a single-mandrel machine requires an interruption in the winding process at the completion of winding each package, as the package is removed from the machine and a new package winding begins. Various dual-mandrel wire winding machines are known in the art. These machines increase efficiency by allowing a package to be wound onto one mandrel while a previously-wound package on the other mandrel is removed by an operator, thus maintaining a continuous output. These machines, however, are mechanically complex, and comprise a large plurality of interworking moving parts, particularly in effecting the transfer of wire from one mandrel to the other. Thus, there exists a need in the art for a dual-mandrel wire winding machine that automatically transfers wire from one mandrel to the other in an orderly, low-cost, mechanically simple manner, while exhibiting high reliability, simplicity, repeatability of operation, and ease of maintenance.